Qualitative evaluation of the blood-brain barrier after the use of hypertonic saline solution in young rats.

The blood-brain barrier (BBB) controls the biochemical environment of the brain with variable permeability when comparing adults to children. Based on the knowledge that there is a greater vulnerability in the BBB of young subjects submitted to biochemical variations in the blood and in the brain, an experimental model was designed to study small volume resuscitation. Young Wistar rats were submitted to hemorrhage and resuscitated with 7.5% NaCl solution before undergoing a qualitative evaluation of their BBB. Thirty male rats were anesthetized and divided into four groups: Group 1 - submitted to hemorrhagic shock restored with hypertonic saline solution (HSS); Group 2 - submitted to hemorrhagic shock without volume restoration; Group 3 - receiving only HSS, and Group 4 - control. The data analyzed were: mean arterial blood pressure, base excess, sodium, chloride, urea, blood osmolarity and blood glucose levels. After infusing a 2% Evans blue solution, qualitative analysis of the BBB was carried out. Group 1 presented final mean blood pressure levels equivalent to groups 3 and 4. Group 2 had a significant difference in the final base excess when compared to the other groups. In groups 1 and 3, mean sodium and chloride, as well as serum osmolarity, were more elevated than groups 2 and 4. Macroscopic examination of the brain did not reveal any changes in color, which could be attributed to the opening of the BBB. It was concluded that the 7.5% NaCl solution in this experimental model did not promote qualitative changes in the BBB. Copyright 2001 S. Karger AG, Basel